Plastic ring pull easy open end

ABSTRACT

An easy open end for a container which incorporates an injection molded, plastic opening feature having no exposed, sharp, bare edges. An adhesive promoting coating system permanently bonds the plastic to the inside surface of the end.

U nited States Patent Platt et al. 1 Oct. 31, 1972 [54] PLASTIC RING PULL EASY OPEN END 3,437,227 4/1969 Peyser ..220/47 Inventors: John Robert Crystal Lake; Eieke Stanley Edward Rohowetz, Barrington, both of [11. Primary Examiner-George T. Hall [73] Assignee: American Can Company, Green- AmmeyRbert Aube' wich, Conn. 221 Filed: June17, 1971 [57] ABSTRACT An easy open end for a container which incorporates [2]] Appl' 154064 an injection molded, plastic opening feature having no exposed, sharp, bare edges. An adhesive promoting 52] us. Cl. .220/54, 220/46 R g/(2131 coating system permanemly bonds the plastic to the In Cl 865! 17/20 inside surface of the end.

[58] Field 0! Search ..220/54, 53, 48, 90.6, 27, 66, i p 220/67, 46 R [56] References cm 10 Claims, 'r nm vin Figures UNITED STATES PATENTS 3,184,096 5/1965 I Cheehey "229/45 1;

l//A I P/ T PATENTEDUCUI I912 3,701,453

SHEEI 1 OF 2 I ll'l JIHIIII 47 v if;

This invention relates to metallic or other type easy open ends for containers, and more particularly to easy open ends having injection molded plastic permanently secured to some parts thereof and detachably'secured to other parts thereof.

Heretofore containers have been provided with various types of easy opening structures to facilitate the emptying or pouring of the contents therefrom. These prior structures have generally been characterized by a tear portion in a panel of the container defined by a weakening line in the panel whereby the tear portion is completely separated from the remaining portion of the panel. Upon such separation, sharp, bare metallic edges are exposed both on the container panel and the separated tear portion. These sharp, unprotected edges are potentially hazardous to' the consumer. This problem of bare edge exposure is solved by the present inventions utilization ofan adhesive plastic member in combination with a preferred design of a line of weakness. I r

In US. Pat. No. 3,184,096, issued to W. E. Cheeley May 18, 1965, there is disclosed an easy open end container which employs sealing means permanently interconnected to the outer peripheral edge of the insert and detachably secured to the inner peripheral edge of the wall of the end closure. The above described embodiment admittedly solves the problem of the removed insert having exposed bare edges, but it still leaves behind a closure wall having sharp, bare edges. In fact, none of Cheeleys disclosed embodiments will result in an opened container having no exposed, sharp, bare edges. The prime reason for this shortcoming in Cheeley is stated in column 4, lines 40 46: the polyethylene or sealing means does not bond to the metal end closure blank, the same is merely placed under compression between the peripheral edges of the insert and wall so that a substantially hermetic seal is created between the insert and wall when the polyethylene subsequently hardens. The instant invention employs an adhesive coating system so that the plastic may be permanently, rather than detachably, secured to the inside surface of the end rim (Cheeleys wall of the end closure), and thereby eliminate all problems of sharp, bare edge exposure.

Cheeley discloses as a sealing means only polyethylene, which cannot provide a true hermetic seal. According to the Modern Packaging Encyclopedia, 1790 issue, pages 148 and 149, high density polyethylene has an oxygen transmission rate of 520 3900 ccJmiI/l sq. m./24 hrs./ 1 atm./73 deg. F., percent R.I-I. (ASTM D 1434). Applicants recommended plastic member shows virtually a zero rate of oxygen transmission, and thereby provides a true hermetic seal. It will become apparent that applicants invention is superior for purposes of vacuum packing or where a hermetic container is desired.

As discussed above, Cheeleys sealing means does not bond to the metal end closure. For this reason, Cheeleys sealing means-metal end interface is not truly hermeticallysealed. It follows that since the sealing means, polyethylene, transmits oxygen at the rate stated above, and since the polyethylene sealing means does not bond to the metal end closure, Cheeleys container cannot be considered to be a hermetic container. Applicant provides an easy open end with plastic which transmits virtually no oxygen, and employs an adhesive coating system to bond the plastic to the container end, thereby providing an hermetic easy open end, which can be joined with a container body to form an hermetrc container.

The containers of the instant invention also provide the advantage over Cheeley of being able to tolerate SUMMARY OF THE INVENTION The present invention provides, in combination, an easy open end of a container comprising a rim and a center panel insert, an adhesive coating system on the inside surface of the end, a sealing, adhesive plastic member detachably secured to the outside surface of the rim and permanently secured by means of the coating system to the inside surfaces of said rim and insert, whereby said insert is sealed to said rim, the plastic member being scored on its inside surface adjacent the inside peripheral edge of the rim, the rim being spaced from the center panel insert so that the plastic member substantially surrounds the panel inserts peripheral surface and outside and inside surfaces adjacent the insert peripheral surface, and handle means having an end interconnected to said plastic member and extending at least partly across said panel insert to provide means for tearing said plastic member along its score,

whereby the panel insert may be separated from the run.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a container incorporating the easy open end of this invention.

FIG. 2 is a sectional view taken on the vertical plane indicated by the line 2-2 of FIG. 1.

FIG. 3 is the same as FIG. 2 except it shows the end after it has been opened.

FIG. 4 is an enlarged fragmentary view of the opened container of FIG. 3 at its score line.

FIG. 5 is a vertical sectional view showing essentially the same end as in FIGS. 1 4, but with slight modification to effect reclosure.

FIG. 6 is the same as FIG. 5 except it shows the end after it has been opened.

FIG. 7 is the end of FIG. 6 after it has been reclosed.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the following description, score line is defined to be a thin section or any line of weakness. Referring now to the drawings, particularly FIG. 1, for a description of the preferred embodiment of the instant invention, there is shown a container generally designated 11, comprising a container body 13, an easy open end 15, and an end closure 17.

FIGS. 2 and 3 show the relationship of the easy open end 15 to the container body 13, and the manner of opening container 11. The easy open end 15 comprises a rim 19 and a center panel insert 21. An adhesive plastic member 23 is detachably secured to the outside surface 25 of the rim 19 and permanently secured to the inside surface 27 of the rim 19 and the inside surface 29 of the center panel insert 21, thereby sealing the insert 21 to the rim 19. The inside surfaces 27 and 29 are covered with an adhesive coating system 31 which enables the plastic member 23 to permanently bond to the inside surfaces 27 and 29 of the end 15.

The plastic member 23 has a score line 33 adjacent the inside peripheral edge 35 of the rim 19. This location of the score line 33 assures that the plastic member 23 will tear at or near the inside peripheral edge 35 of the rim 19, so that after opening of the container 11, there will remain no exposed, sharp, bare edges. Since the plastic member 23 is not permanently bonded to the outside surface 25 of the rim 19, the plastic member 23 separates from the rim 19 along the outside surface 25, thus assuring that the outside peripheral surface 37 as well as the inside surface 29 and the outside surface 39 adjacent the peripheral surface 37 of the insert 21, are substantially surrounded by the plastic member 23 after the container 11 is opened by the user thereof.

Handle means in the form of a plastic ring pull tab 41 having an end 43 thereof interconnected to the plastic member 23 extend at least partly across the panel insert 21 to provide the user with easy means for opening the container 1 1.

Although it may not be necessary, it may be desirable to include a release coating or film on the outside surface 25 of the rim 19 to assure a smooth and easy separation of the insert 21 and the plastic member 23 permanently bonded thereto from the rim 19.

FIG. 4 shows how the plastic member 23 tears from the score 33 to the inside peripheral edge 35 of the rim 19, leaving no exposed, sharp, bare edges. Even if the remaining plastic member 23 does not cover the entire inside peripheral surface 47 of the rim 19 after opening, it is sufficient to eliminate sharp, bare edge exposure because the plastic member 23 does remain secured to the area adjacent the inside peripheral edge 35. This minimum coverage of the edge 35 is guaranteed by the location of the score line 33 adjacent the edge 35. In many instances, the plastic member 23 tears in such a manner as to leave parts of the inside peripheral surface 47 coveredwith plastic member 23.

FIGS. 7 illustrate the same end as in FIGS. 1 4 but with slight modification, primarily in the rim 19, so that the end may be reclosed after opening. The reclosure feature is achieved by providing the rim 19 with an area of undercut 49 into which the center panel insert 21 may be snapped after the original opening of the container.

The end may be comprised of tin free steel, electrolytic tin plated steel (ETP) or aluminum. It is also possible to employ various metal-plastic laminates for the end 15 It was found that the most suitable release coating $51; an epoxy urea formaldehyde, such as Midlands V A recommended adhesive coating system 31 comprises a base coat on the inside rim surface 27 and the inside panel insert surface 29 such as Celanese epoxy urea formaldehyde 7164X together with a top coat such as Mortons ethylene acrylic acid copolymer Adcote 37F-l on the base coat. The base coat is employed primarily for corrosion resistance, while the top coat provides adhesion between the plastic and the base coat. Ifthe contents of the container are not of a corrosive nature, then the adhesive coating system 31 may consist of only the top coat.

The adhesive plastic member 23 to be used in combination with the above adhesive coating system 31 should comprise, by weight, 20 60 percent matrix resin, 10 30 percent plasticizing resins, l0 50 percent inorganic filler and l to 5 percent pigment. The addition of 1-10 percent by weight of elastomers and small percentages of stabilizing materials used in the plastic molding art may be employed for obtaining various desired product and processing properties. One such plastic is as follows:

l. The MX 2375.12 is Dow Chemicals 8 percent acid matrix resin ethylene acrylic copolymer having a melt index of about 6. This resin is used as the primary matrix adhesive with medium strength and melt flow properties. It is also a copolymer having acid content which gives a bond to a suitable substrate such as polymers or other metals.

2. The BAA 9500 is Union Carbides 18 20 percent ethylene acrylic copolymer with a melt index of 300. It is a plasticizing resin added to increase the melt flow rate and to provide added acidity for bond formatlon.

3. The C-l026 is Chemplex Co.s 0.915 density polyethylene with a melt index of 23. It is a plasticizing resin added for strength and flow, and is compatible with the matrix copolymer. This low density polyethylene helps the material flow more easily into the fabricating mold. Y

4. The Novacite L207A is a natural silica filler from Malvem Minerals. It is used because of its small particle size of 3 10 microns, and its rounded, flat shingle particle shape. It is non-abrasive, forms strong bonds to copolymers in moist environments, and has a good packing density which reduces permeation rates.

High filler loadings reduce the tear strength of the plastic composition (a distinct aid in opening) without unduly reducing the peel or lap shear bond strengths. Other advantages include improved heat transfer rates (20 times resin alone) and cost reduction.

5. Zopaque R69 is Glidden Durkees titanium dioxide pigment. It is employed for its fine particle size and EXAMPLE ll Ingredient by Weight 1. DQDA 2600 45 2. Novocite L207A 32.5 I 3. Dylan l5 4. Super Dylan 5 5. Zopaque R69 2.5

The DQDA 2600 is Union Carbides 8 percent acid matrix resin ethylene acrylic copolymer, and is similar to the MX 2375.12. The Dylan is Sinclair Koppers low density polyethylene, while the Super Dylan is Sinclair Koppers high density polyethylene.

Each of the example plastics were utilized in manufacturing an easy open end according to the present invention. Midland's V732 was used as the release coating. The adhesive coating system consisted ofa base coat of Celanese epoxy urea formaldehyde 7164X and a top coat of Mortons ethylene acrylic acid copolymer Adcote 37F-l. Ends made of the two examples are still being tested on completed containers. Example I has gone 49 days without any measurable oxygen permeation, while Example II has gone 6 months without any measurable oxygen permeation.

Considerable latitude in composition is possible. Higher temperature capability is achieved by substitutin g a higher density polyethylene for the C-1026.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the article and that changes may be made in the steps of the method described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

What is claimed is:

1. In combination, an easy open end of a container comprising a rim and a center panel insert, an adhesive coating system on the inside surface of said end, a sealing, adhesive plastic member detachably secured to the outside surface of the rim and permanently secured by means of said coating system to the inside surface of said rim and insert, whereby said insert is sealed to said .rim, said plastic member being scored on its inside surface adjacent the inside peripheral edge of the rim, the

rirn being spaced from the center panel insert so that the plastic member substantially surrounds the panel inserts outside peripheral surface and outside and inside surfaces adjacent the insert peripheral surface, and handle means having an end interconnected to said plastic member and extending at least partly across said panel insert to provide means for tearing said plastic member along its score, whereby the panel insert may bese atedfromt eri 2. The combination 0 claim 1 wherein the outside surface of the rim is covered with a release coating, and the easy open end is comprised of ametal.

3. The combination of claim 2 wherein the inside peripheral surface of the rim is located beneath the outside peripheral surface of the panel insert.

4. The combination of claim 3 wherein the handle means comprises a plastic, ring pull tab, and the easy open end is comprised of a metal-plastic laminate.

5. The combination of claim 3 wherein the rim is provided with an undercut in the area adjacent the plasticenclosed center panel insert into which said insert may be snapped after opening of the container.

6. The combination of claim 5 wherein the adhesive plastic member comprises by weight 20 to percent matrix resin, 10 to 30 percent plasticizing resin, 10 to 50 percent inorganic filler and 1 to 5 percent pigment.

7. The combination of claim 6 wherein the adhesive coating system comprises a base coat of an epoxy urea formaldehyde and a top coat of an ethylene acrylic acid copolymer.

8. The combination of claim 7 wherein the release coating comprises an epoxy urea formaldehyde.

9. The combination of claim 8 wherein the matrix resin comprises an ethylene acrylic copolymer, the plasticizing resin comprises ethylene acrylic copolymer and low density polyethylene, the inorganic filler comprises natural silica, and the pigment comprises titanium dioxide.

- 10. The combination of claim 9 wherein the easy open end is hermetic. 

2. The combination of claim 1 wherein the outside surface of the rim is covered with a release coating, and the easy open end is comprised of a metal.
 3. The combination of claim 2 wherein the inside peripheral surface of the rim is located beneath the outside peripheral surface of the panel insert.
 4. The combination of claim 3 wherein the handle means comprises a plastic, ring pull tab, and the easy open end is comprised of a metal-plastic laminate.
 5. The combination of claim 3 wherein the rim is provided with an undercut in the area adjacent the plastic-enclosed center panel insert into which said insert may be snapped after opening of the container.
 6. The combination of claim 5 wherein the adhesive plastic member comprises by weight 20 to 60 percent matrix resin, 10 to 30 percent plasticizing resin, 10 to 50 percent inorganic filler and 1 to 5 percent pigment.
 7. The combination of claim 6 wherein the adhesive coating system comprises a base coat of an epoxy urea formaldehyde and a top coat of an ethylene acrylic acid copolymer.
 8. The combination of claim 7 wherein the release coating comprises an epoxy urea formaldehyde.
 9. The combination of claim 8 wherein the matrix resin comprises an ethylene acrylic copolymer, the plasticizing resin comprises ethylene acrylic copolymer and low density polyethylene, the inorganic filler comprises natural silica, and the pigment comprises titanium dioxide.
 10. The combination of claim 9 wherein the easy open end is hermetic. 